OK if I am rading this right that is high teens s total AFTC advance? cAN BE A BAD PICKUP OR phasing kind of weird. Harder to start when hot?
Was not hard to start while hot. With the EFI system, start up is pretty consistent.OK if I am rading this right that is high teens s total AFTC advance? cAN BE A BAD PICKUP OR phasing kind of weird. Harder to start when hot?
Current thermostat is 185, keeps operating temp pretty steady on a hot day between 195-205, depending on if I'm in stop/go traffic or on the highway.What stall, rear gear, and tire roll-out? this will play an important roll in avoiding detonation on a long pull. Detonation and it's sometime partner pre-ignition, is the enemy of your engine, and has to be avoided at all costs. They break things like pistons and rings and hammer out bearings.
I'm trying figure out why you would chose all-in at 2200; and no vacuum advance. That is a race-car tune, with a lightweight car, a big engine, and race gears.
For you tho;
For fuel-economy reasons, as well as a bit of WOT power;
you will need to push the minimum cooling system temp up to at least 180*, Myself; I would try for 195. But your cooling system will have to be rock-steady without any hunting around. You will have to make it so. You cannot begin your tune until the cooling system is at a fixed and steady temperature; whether it be 195 or 180, or whatever it is; it has to remain stable for the tune. Later you can add temperature compensation.
And your engine will HAVE to have a source of fresh cold air. If the inlet air temp is bopping up and down, from 100* to 400*F you will have a big tuning headache.
Ok so, you should know that the more idle timing you give it, with no other changes, the higher the idle will climb. This is not necessarily a good thing. Your automatic transmission equipped engine will never be asked to pull at idle, so at the beginning of your tuning, it can be whatever. Later, much later, you can start to monkey with that. So, your engine doesn't much care about it's idle timing, as long as throttle response doesn't fall on it's face between idle and it's stallspeed. But beginning at the stall speed is where it starts to care. From there to ~3200 it is almost critical to not have too much, and after 3600 most engines fall to between 32* and 36*.
So,
Confirm your timing index mark.
reset the idle timing to 10 degrees advance.
reset your idle rpm to 600 in Neutral, or 550 in gear whichever is less.That stock engine should idle down to 600in gear, no problem.
Now increase your idle timing to 12/14* and leave it there.
Now program your computer with a linear power-curve to be 26* at 2800; and then change to a slower linear curve to be 34* all in at 3600. That is your starter POWER CURVE. It will only be near-correct at WOT. It will not be correct at any other throttle/load setting. I repeat; it will not be near-correct at any other throttle/load setting except WOT.
All other throttle settings and rpms are adjusted by the load sensor, AKA the vacuum advance. This timing is added to the power curve in direct proportion to manifold vacuum, which is 100%dependent on the load factor or throttle opening versus rpm, AKA speed-density.
So lets say you are cruising along at 50 mph in top gear at 2400 rpm. Your engine might like 56* of timing there; IDK, just saying. But if you give it any throttle there as in; you came to the bottom of a kill,then, at 56* and 2400rpm, it will only take a few seconds (15 seconds@2400rpm is 600 revolutions times 4 firings per revolution is 2400 hammer-blows, or 300 per piston)until the factory pistons may begin to fail; IDK how much they can take, but the rod bearings may fail first. Therefore,the "vacuum advance" will have to immediately start to decrease linearly with throttle opening (manifold vacuum), back to the power-timing,which might be 20/22*@2400( just guessing) which I purposely made weak for this reason. Once climbing up that hill, your "vacuum advance" will have to stay at zero, while the engine is stuck in top gear at 2400rpm, on the SAFE power-curve.
If you were to downshift,at this moment, with a 727, the Rs would jump from 2400 to ~4100, and the engine would be on the all-in timing of 34*@3600, and if you have sufficiently enough octane rating, it will pull itself along nicely. Perhaps nicely enough that manifold vacuum might rise high enough to again bring in some "vacuum advance". This might be a good thing but could just as easily be bad; that is for YOU the operator and tuner, to determine. To help you with this, your EFI may have a knock-sensor tune available, and I highly recommend that you use it.
So some of these things have already been mentioned, I just put them all in the same post, and added some reasons why, to help you understand.
The info from AJ is to set TWO different slopes on the advance curve... one from idle to 2800 RPM and a slower slope from 2800 to 3400. But from your descriptions of the computer settings, you can only set one slope on the curve, from idle to the end RPM (Unless you can choose in an earlier menu to have 2 slopes in the curve).I didn't follow the "start with setting your curve at 26* at 2800, and then change it to be these other settings." Why do one and then the other?
Correct. It's a single slope interface. Sounds like I should use the more conservative slope?The info from AJ is to set TWO different slopes on the advance curve... one from idle to 2800 RPM and a slower slope from 2800 to 3400. But from your descriptions of the computer settings, you can only set one slope on the curve, from idle to the end RPM (Unless you can choose in an earlier menu to have 2 slopes in the curve).
I've checked and locked in the base timing at 12 degrees via the "set base timing" workflow through the app. Timing light on wire #1 shows it right at 12, though the markings are a little hard to see. Worse case scenario I might be a degree or two off in one direction or the other, but that'd have little impact overall as I'm tuning.There is lots of good advice here, the only problem is most of it with the exception of the total and initial timing only apply if you’re running the factory distributor and vacuum can.
First off make sure you set the distributor per Edelbrocks instructions at 12* By locking the timing with the tablet And verify by timing light assuming you’re balancer is good. Then set your initial 16-20* and total in timing as suggested earlier to all in 32ish * at say 3600.
Adding vacuum advance with the Pro Flo 4 WILL affect idle timing slightly.
The most important takeaway here is to verify the 12* with the timing locked out because if this is off the computer has no was to know where the timing is And all other timing parameters will be off. The advice you received on the tech forum over there for 22* at 2200 was BS.
Report back with results but from my playing with this system it does not like anything more than 34-36* total without the backfire issues.
It's a totally legit question, and why I don't want to guess what tweaks were done.I am not home right now but I have the FSM for 78 Motorhomes and they do have 2 stage advances . Plus the vacuum advance.
My question about emmissions was because I wasnt sure if heavy vehicles fell under the laws at that time . I remember 3/4 and 1 ton trucks still ran leaded fuel into the 80s.
It's a totally legit question, and why I don't want to guess what tweaks were done.
It might have been cat exempt in '78 (like the pickups) but may have met some emmissions requirements - especially for idle and decel - in addition to vapor recovery and PCV.
They were catalytic exempt. I can recall being told this in a Ford dealership back in '76. I asked why the F150.... before that, they jumped from F100 to F200, and the 'new' F150 gave them the chance to make a high enough weight rating in a 1/2 ton chassis to not put in the catalytic converter. Sorta a 5/8 ton rating, I guess LOLI am not home right now but I have the FSM for 78 Motorhomes and they do have 2 stage advances . Plus the vacuum advance.
My question about emmissions was because I wasnt sure if heavy vehicles fell under the laws at that time . I remember 3/4 and 1 ton trucks still ran leaded fuel into the 80s.
The backfiring in neutral (non engine load to speak of) does not suggest detonation. Detonation is a heavy load thing... when the throttle is open wide, cylinder filling is high, and consequently peak pressures are high.Anytime the engine was under load, things were not running smoothly. I could even get it to consistently backfire just by revving the engine up to 3000 rpms in park.
A darned good question......I May have missed it in previous posts but did you lock up the mechanical advance in the dizzy as the ecu controls the spark except vacuum advance ?